This invention relates to a forming device to be practiced in a coil spring forming machine and a method of replacing said device, more particularly to a constitution in the forming machine for forming a coil spring by winding a heated rod or wire-shaped spring material (spring material), wherein a cassette mechanism, composed of a major section which performs wind-forming corresponding to the desired type of spring as a single holder unit is removable from the body of the forming machine, and to a method of replacing said cassette, wherein an appropriate type of such cassette mechanism can be selected for respective requirements for forming the desired spring, and replaced therewith.
In a prior art equipment for forming coil springs, provided are a feeding machine for feeding and guiding horizontally a spring material freshly removed from a heating furnace through and along each roller, and also a forming machine disposed in a direction perpendicular to the forwarding end of said feeding machine, in which said material is wound around a mandrel while it is guided by a lead screw to determine the pitch of the resulting spring. When a spring is formed by use of such equipment, said equipment may have an embodiment essentially as shown schematically in FIG. 20. To describe in detail, said spring material is forwarded to a predetermined position by the feeding machine; the starting end (head end) of said material W is then brought to be in alignment with the starting end of the lead groove 60a of the lead screw 59a in the forming machine and simultaneously positioned by the chucking piece 103a of a chucking device disposed at the starting end of the mandrel 50a to be fixed thereby; thereafter the material W is serially wound to be formed into a spiral while it is guided by the synchronous rotation of the mandrel 50a and the lead screw 59a which are driven by a driving device 17a disposed in the forming machine, to determine the pitch; and finally the tail end portion of the material (end of the spring seat) is wind-regulated by a tail end regulating device 115a.
After completion of this winding operation, the starting end of the coil spring thus formed is released from the chucking device, and then the coil spring is removed from the mandrel relative to the movement of the mandrel when it is once removed from the forming machine from the side of the support of said machine by retracting it in the axial direction thereof. Said mandrel is advanced again to be reset at the predetermined position in the side of the support of the machine, whereby preparation for another cycle of spring forming is completed.
Thereafter, the process comprising the steps of feeding and winding the material, forming a spring and removing it will be repeated as described above.